Issue using lsqcurvefit function - App Designer

Good morning,

I'm new to App Designer, and I need to solve an optimization problem using the lsqcurvefit function.

I reuse pre-existing calculation codes, I defined a function

F1=myfun_root(app,x,Speed_sample_RPM)

as a private function in the application code. In this same code, I call the lsqcurvefit function in a CallBack Button:

[x,resnorm,residual,exitflag,output] = ...
        lsqcurvefit(@myfun_root,app.x0,Speed_sample_RPM_zoom_T,yt_sample_zoom_Total_Nondim,app.lb,app.ub);

All the variables used are defined previously in the code, which I cannot copy/paste here.

When I run the application and click on the button to calculate the interpolation which launches the CallBack including the lsqcurvefit function, I get the error message:

Error using nargin
Function myfun_root does not exist.

While the latter is well defined as a function at the beginning of the program.

I searched on the Q/A of Matlab but I did not find an already existing answer to this concern, of which I do not understand the cause.

Could someone please enlighten me?

I thank you in advance !

[Torsten]

While the latter is well defined as a function at the beginning of the program.

As a function handle ? If it is defined as a function, it must be included at the end of the program (script).

Answer 1

[Cris LaPierre]

Since you didn't share your code, I created a simple example in app designer using this example from the lsqcurvefit documentation page. I made the following observations after comparing to what you've shared.

You haven't defined your function correctly. I would expect it to look something like this

function F1=myfun_root(app,x,Speed_sample_RPM,Speed_sample_zoom)

In addition, your calling syntax needs to be modified to work inside app designer.

[x,resnorm,residual,exitflag,output] = ...
                lsqcurvefit(@app.myfun_root,app.x0,Speed_sample_RPM_zoom_T,yt_sample_zoom_Total_Nondim,app.lb,app.ub);

This of course assumes all other variables have been propertly defined.

[Hélène]

Thank you for your two answers which made it possible to solve this first problem. @Cris la Pierre I'm not sure I understand adding a third argument to the F1 function.

When I run the code now I get another error message:

Error using assert
FUN must have two input arguments.

However, the myfun_root function has two input arguments, x0 and Speed_sample_RPM_zoom, so I don't really understand the correction to be made.

I'm sorry, this may seem basic to you, but I'm new to Matlab on the one hand and App Designer on the other.

I thank you in advance !

[Cris LaPierre]

That was me trying to take a guess at what your code was doing. I had to try a couple things to get the example to run in App Designer, and just didn't go back and minimize the code.

You can remove the 3rd input argument from myfun_root

function F1=myfun_root(app,x,Speed_sample_RPM)